(1) Field of the Invention
This invention relates to a high concentration surfactant slurry having a reduced viscosity. More particularly, it relates to a high concentration surfactant slurry containing at least 50% by weight of a higher alcohol ethoxylate sulfate salt as an effective surfactant ingredient, in which a special additive has been incorporated whereby the slurry viscosity is reduced and the storage stability is enhanced.
(2) Description of the Prior Art
A salt of a higher alcohol ethoxylate sulfate (which salt is hereinafter referred to as "AES" for brevity) is ordinarily used in the form of a homogeneous transparent solution, containing AES at a concentration lower than the solubility in order to ensure the homogeneity of the quality. However, from the viewpoints of increasing the efficiency of utilization of a storage tank and making the transportation of the slurry more economical, and in order to increase the drying efficiency and reduce the quantity of heat when AES is used as the raw material for a granular detergent, it is preferred that AES be used in the form of a high concentration slurry. A high concentration slurry of such a surfactant has a high viscosity and is difficult to handle. Therefore, it is necessary to reduce the viscosity of the slurry. From the viewpoint of easiness in handling, it is ordinarily desired that such a high concentration surfactant slurry should have a viscosity lower than 80 poises at a temperature of from 25.degree. to 60.degree. C. A high concentration AES slurry containing at least 50% by weight of AES is used for heavy detergents, light detergents, shampoos, or the like. When the slurry is used for such purposes, it is also desired that the properties of the slurry should not be affected by the temperature of the slurry and that the slurry should be able to be handled easily at low temperatures.
As means for solving these problems, there is known a method in which polyethylene glycol is added to the slurry (see Japanese Laid-Open Patent Application No. 116,383/75). Furthermore, we previously found that a high concentration AES slurry, having incorporated therein a salt of a polyethylene glycol sulfuric acid diester having a specific molecular weight (Japanese Laid-Open Patent Application No. 36,596/81) or a polyoxyethylene glyceryl ether (Japanese Patent Application No. 22,549/80), has a reduced viscosity and is not affected by temperature and this slurry can be handled easily at low temperatures.
These merits of the low viscosity, high concentration AES slurry containing the above additive are sufficiently manifested when the slurry is used within a short period from the preparation thereof or is stored in a storage tank equipped with a stirrer; but, when the slurry is stationarily stored for a long time, undesirable phase separation takes place and the quality becomes non-uniform. Therefore, if the slurry is stored for a long time in drums or other containers, the commercial value is drastically lowered.